Region searcher and method of driving the same and code searcher using the same

ABSTRACT

A region searcher, a method of driving the same, and a code searcher using the same are disclosed. When a predetermined region is iteratively searched, the energy value corresponding to the same hypothesis location value is stored by using a searcher having divided two buffers, thereby the implementation complexity thereof can be remarkably reduced, without using a simple memory. 
     In addition, in case where the region is iteratively searched in the state of the deteriorated signal-to-noise ratio to find the energy value at one hypothesis location and in case where the region must be iteratively searched because of the restriction which the size of the matched filter can be not increased, the implementation complexity thereof can be remarkably reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a region searcher, a method of drivingthe same, and a code searcher using the same, in particular, a regionsearcher which the complexity of the implementation thereof can beremarkably reduced by storing the energy value corresponding to the samehypothesis location value by using a searcher having divided twobuffers, without simply using a memory, when a predetermined region isiteratively searched.

2. Description of the Prior Art

Generally, in the code division multiple access type cellular radiotelephone communication system, the location of the spread code must befound. For this, there are a method using an active type correlatorstructure and a method using a passive type matched filter structure.

The method using the active type correlator structure is used in aterminal and so forth, because the structure thereof is simple. However,there is a problem that the signals must be collected for a long time inorder to use the signal required for increasing the gain of a receivedsignal. In addition, in this method, the used signal can not berepeatedly used, and the searching time thereof becomes longer than thatof the method using the matched filter, because the signals arrived inthe different time are collected and used as the location information ofthe spread code.

In the method using the matched filter structure, the received signalsare stored in a buffer in received order and are multiplied by anexpected input signal, thereby the sum of products is used as thelocation information of the spread code. Accordingly, since the locationinformation of the spread code for every input signal sample isgenerated, the region can be searched at high speed. However, in orderto obtain the needed signal gain, the length of the buffer must be long.Also, because the operation thereof is accomplished at the signal rateof the input sample, the structure thereof is complicated and the powerconsumption becomes increased.

FIG. 1 is a block diagram of a spread code searcher used in aconventional code division multiple access (CDMA) type cellular radiotelephone communication system.

Referring to FIG. 1, the spread code searcher comprises a matched filter10, an energy value converting section 11, an address generating section12, a first memory section 13, and a second memory section 15.

The matched filter 10 receives in-phase signal (I data) andquadrature-phase signal (Q data), constructs the matched filter typestructures using a predetermined spread signal pattern, and outputs thecorrelated values of the input signal. In this case, the correlatedvalues are output to the energy value converting section 11 at everyhypothesis location, and the energy value converting section 11 squareseach of phase signals, and adds them to be converted to an energy value,such that each of the phase components in the in-phase signals and thequadrature-phase signals due to Rayleigh fading effect of the channelincluded in the correlated value is removed. Such obtained values existin the hypothesis location in all.

In addition, if the signal-to-noise ratio thereof is very small, theobtained energy value therein is very small. Therefore, the energyvalues are iteratively obtained and are added them in order to increasethe signal value. For performing such operation, the energy valueobtained at the each of the hypothesis location is stored in the firstmemory section 13 so as to be added to a value that is newly obtained atthe same hypothesis location. In case of constructing the structure byusing the first memory section 13, an address for controlling the firstmemory section 13 must be generated in the address generating section.Also, the second memory section 15 for finding and storing the largestvalue among the values stored in the first memory section 13 is furtherneeded.

In the code division multiple access type cellular radio telephonecommunication system, in order to find such a spread code location, aknown signal having the inherent orthogonal characteristics istransmitted in case of a forward link which a base station transmits asignal to a terminal, and an inherent code signal using the highself-correlated property is transmitted in case of a reverse link whicha terminal transmits a signal to a base station. Since these signals areused within the limited signal power in the overall system, the power ofthese signals cannot become larger than the certain limit.

In case where the location information of the spread code is obtained asmentioned above, when the power of the signal obtained at a time is notenough to determine the location, the signals are iteratively obtainedat the searched region and are added to the previous obtained value,thereby the signal having the larger value can be obtained. At thistime, if the size of the searched region is increased, in order to storethe information therefor, a device for storing information having thevalue corresponding to the spread code location included in the searchedregion is needed.

SUMMARY OF THE INVENTION

Thus, the object of the present invention is to make an effective regionsearcher using a device of small size storing elements, in order tosolve the above-mentioned problem that the information for the allspread code location included in the region must be stored.

In accordance with one aspect of the present invention, there isprovided a region searcher comprising an input signal converting sectionfor receiving an energy value and converting the energy value; a firstbuffer section and a second buffer section for the energy valueconverted by said input signal converting section; a comparing sectionfor comparing an input location value with a location value stored insaid second buffer section in order to search the location value storedin the second buffer section; an output signal converting section forconverting an energy value stored in said second buffer section; and anadder for adding the energy value output from said input signalconverting section and the energy value output from said output signalconverting section and storing the added value to the second buffersection.

In accordance with another aspect of the present invention, there isprovided a method of driving a region searcher comprising a first stepfor setting a variable; a second step for receiving an input energyvalue and an input location value by using an input signal convertingsection and an index comparing section; a third step for comparing saidinput location value with a location value stored in said second buffersection by using said index comparing section; a fourth step forconverting said input energy value by a predetermined energy value ratioby using said input signal converting section, if said input locationvalue is not equal to the location stored in said second buffer sectionin the third step; a fifth step for comparing the energy value convertedin the fourth step with the energy value stored in said first buffersection, and, if the converted energy value is larger than the energyvalue stored in said first buffer section, replacing said convertedenergy value with an smallest energy value among the energy valuesstored in said first buffer section, and, if so not, receiving a newenergy value; a sixth step for converting the input energy value and theenergy value stored in said second buffer section by using apredetermined energy value ratio if said input location value is equalto the location value stored in said second buffer section in the thirdstep; and a seventh step for removing the energy value stored in thelocation of said second buffer section corresponding to the inputlocation value in order to store the energy value converted in the sixthstep, aligning the energy values in the second buffer section inaccordance with the size thereof, and storing said added energy valuesthereto.

In accordance with further another aspect of the present invention,there is provided a code searcher comprising a matched filter forreceiving input signals including in-phase and quadrature phasecomponents and outputting the correlated value of said input signals; anenergy converting section for squaring the in-phase and the quadraturephase and adding them to be converted to an energy value, in order toremove the in-phase and quadrature phase components included in saidcorrelated value; an index generating section for generating a locationvalue corresponding to said energy value; and a region searcher havingthe structure according to claim 1 for receiving the energy value outputfrom said energy value converting section and the location valuegenerated by said index generating section to detect a code spreadsignal.

In accordance with the further another of the present invention, thereis provided code searcher comprising a correlator for receiving inputsignals including in-phase and quadrature phase components andoutputting the correlated value of said input signals; a code generatingsection for generating and outputting a code spread signal in successivecode searching regions without the loss of calculation time; an energyconverting section for squaring said in-phase and quadrature phase andadding them to be converted to an energy value in order to remove thein-phase and quadrature phase components included in said correlatedvalue; an index generating section for generating a location valuecorresponding to said energy value; and a region searcher having thestructure according to claim 1 for receiving the energy value outputfrom said energy value converting section and the location value of saidindex generating section to detect the code spread signal.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

FIG. 1 is a block diagram of a spread code searcher used in a generalcode division multiple access (CDMA) type cellular radio telephonecommunication system.

FIG. 2 is a block diagram of a region searcher according to anembodiment of the present invention.

FIGS. 3 a and 3 b is flowcharts explaining the operation characteristicsof the region searcher shown in FIG. 2.

FIG. 4 is a block diagram of a matched filter code searcher using theregion scanner shown in FIG. 2.

FIG. 5 is a block diagram of a correlator code searcher using the regionscanner shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the embodiments of the present invention will be explainedwith reference to the accompanying drawings.

FIG. 2 is a block diagram of a region searcher according to anembodiment of the present invention.

Referring to FIG. 2, the region searcher according to the presentinvention comprises an input signal converting section 20, a first stagebuffer section 21, a second stage buffer section 22, an index comparingsection 23, an adder 24, and an output signal converting section 25.

Where, the first stage buffer section 21 is connected with the inputsignal converting section 20 for converting the value of the inputsignal including the energy value and the location value, and the secondstage buffer section 22 is connected with the output signal convertingsection for converting the energy value of the second stage buffersection 22. Also, the adder 24 for adding the energy value output fromthe input signal converting section 20 and the energy value output fromthe output signal converting section 25 and storing the added value tothe second stage buffer section 22 is connected between the input signalconverting section 20 and the output signal converting section 25.

In addition, the first stage buffer section 21 stores the large energyvalues by the allowable number among the energy values searched in afirstly searched region. Subsequently, in the iteratively searchedregion, the large energy values among the energy values in the locationswhich are different from the location value stored in the second stagebuffer section buffer 22 are stored in descending order. The secondstage buffer section 22 stores the results searched in a searchedregion, that is, the energy values corresponding to the locations of thevalues stored by the iterative searching operation.

Also, when the region is iteratively searched, index comparing section23 compares the location value input to the index comparing section 23and the location values stored in the second stage buffer section 22. Atthe comparison result, if there is an input location value is equal tothe location value stored in the second stage buffer section 22, theadder 24 adds the energy value output from the input signal convertingsection 20 and the energy value output from the output signal convertingsection 25. In this case, the output signal converting section 25 has acorresponding energy value of input location value equal to the locationvalue stored in the second stage buffer section 22. The added result isstored to the second stage buffer section 22. At this time, the firststage buffer section 21 stores the converted energy values and thelocation values by the allowable number in the first stage buffersection 21 in input energy sequence order, except for the locationvalues stored in the second stage buffer section 22.

On the other hand, when the searching operation for the searched regionis finished, only energy values having the number of energy valuesstorable in the second stage buffer section 22 are stored to the secondstage buffer section 22. The energy values were selected from thehighest energy value in order of the magnitude of energy values amongthe energy values stored in the first and second stage buffer section 21and 22. The contents of the first stage buffer section 21 are removed,and the searching operation for the next searched region is prepared.This operation is iteratively performed to store the values obtained atthe same region to the first stage buffer section 21 and the secondstage buffer section 22, and, when the searching operation for onesearched region is finished, the energy values and the location valuesaligned according to the size thereof are stored to the second stagebuffer section 22. When the searching operation for the given searchedregion is finished, the location values stored in the second stagebuffer section 22 become the desired final region information.

FIGS. 3 a and 3 b are flowcharts explaining the operationcharacteristics of the region searcher shown in FIG. 2.

Referring to FIGS. 3 a and 3 b, firstly, the step S10 is the step forsetting variables. In the step S10, the number of iteration, the numberof the region, the size N1 of the first stage buffer section 21, thesize N2 of the second stage buffer section 22, the ratio R1 of thesignals input to the first stage buffer section 21, the ratio R2 of theinput signal and the value of the second stage buffer section 22 whenthey are added each other are set as the variables. Also, the inputsignal is composed of the location value and the energy value, and isinput from a hypothesis location of the searched region.

In addition, the input speed is determined by sampling the input signalin case of the method using the matched filter, and is determined by theintegration region of a integrator in the correlator in case of themethod using the correlator. Also, the values in the all buffers arereset to ‘0’ at the first operating time. After the location valueswhich are obtained when the operations are performed by the number ofiteration and the energy value thereat are read, the operation forresetting to ‘0’ is performed again.

Next, when the input location value and input energy value are input, itis determined whether the input location value is included in thesearched region (S20). If the input location value is included in thesearched region, it is determined whether the input location value isequal to the location value stored in the second stage buffer section 22(S30). In the step S30, if the input location value is not equal to thelocation value stored in the second stage buffer section 22, the inputenergy value is converted by using the ratio R1, and the converted valueis compared with a smallest value among the values stored in the firststage buffer section 21 (S40 and S50). In the step S50, if the convertedvalue is larger than the smallest value, the input location value andinput energy value are replaced with the smallest value of the firststage buffer section 21 (S60).

On the other hand, in the step S50, the converted value is smaller thanthe smallest value, a new input value is received again (S20). In thestep S30, if the input location value is equal to the location value ofthe second stage buffer section 22, the input energy value and the valuestored in the second stage buffer section 22 are converted by using thegiven ratio R2, and the converted values are stored in the second stagebuffer section 22 (S70). In the step S70, the new value to be stored tothe second stage buffer section 22 is calculated as the followingequation (1), and the energy value and the location value in the secondstage buffer section 22 equal to the input location value are removed,the lowest buffer therein is emptied in order to arrange the values indescending order. The other words, in the step S70, the values are notformally stored to the second stage buffer section 22 according to thesize thereof, but are temporarily stored to position the values ataccurate locations in the second stage buffer section 22. Where, Data isa new energy value, DATA is an input energy value, and Prev-DATA is anenergy value stored in the second stage buffer section 22.Data=DATA*R2+Prev-DATA(1−R2)  (1)

Next, in order to find the location where the new energy value is to bestored, it is determined whether there is a region to store new energyvalue in the second stage buffer section 22, and, if there is an regionto store, the new energy value is compared with the energy values storedin the second stage buffer section 22. At the comparison result, if anenergy value stored in the second stage buffer section 22 smaller thanthe new energy value is detected, the energy value and the energy valuesin the buffers lower than that are downwardly shifted to make thelocation which allow the large value to be inserted. By this operation,the values of the second stage buffer section are converted and storedin descending order (S80 to S100).

Subsequently, returning to the step S20, the input value is received,and if the searching operation for the given searched region is finishedin the step S20, the operation for aligning the values stored in thefirst stage buffer section 21 and the second stage buffer section 22 tothe second stage buffer section 22 in accordance with the size thereofis performed. The value at the highest location in the first stagebuffer section 21 is compared with the values of the second stage buffersection 22, beginning at a largest value thereof, and, if the value islarger than the value stored in the second stage buffer section 22, thevalues of the second stage buffer section 22 smaller than the value ofthe first stage buffer section 21 are downwardly shifted one by one andthe smallest value is removed from the second stage buffer section 22.The values of the first stage buffer section 21 are compared with thevalues of the second stage buffer section 22 one at a time, thereby thevalues of the second stage buffer section 22 are corrected.

In the step S110, the value stored at highest buffer in the first stagebuffer section 21 is fetched and ‘0’ is inserted thereto. In the stepS130, the energy value fetched from the first stage buffer section inthe step S110 is compared with the energy value at any one location inthe second stage buffer section 22. If the fetched energy value islarger than the energy value of the second stage buffer section 22, theprocess moves into the step S140. In the step S140, a smallest energyvalue in the second stage buffer section 22 is removed, the energyvalues smaller than the value of the fetched from the first stage buffersection are downwardly shifted one by one, and an empty buffer isgenerated, thereby the location value and the energy value in the firststage buffer section 21 are inserted to the empty buffer. In the stepS150, it is determined whether there is an energy value to be fetched inthe first stage buffer section.

On the other hand, in the step S130, if the fetched energy value issmaller than the energy value of the second stage buffer section 22, theprocess moves into the step S120. In the step S120, it is determinedwhether there is any other location value to read in the second stagebuffer section 22. If it exists, the next location value in the secondstage buffer section 22 is read. Subsequently, the energy value storedtherein is read and the process moves into the step S130. By thisprocess, if there is no any energy value of the second stage buffersection 22 to be compared with the fetched energy value, the operationfor comparing the value in the first stage buffer section with allvalues in the second stage buffer section 22 is finished, and the nextvalue of the first stage buffer section 21 is read and compared with thevalues of the second stage buffer section 22. By this process, if thereis no any value of the first stage buffer section 21 to be compared withthat of the second stage buffer section 22, the process moves into thestep S160. In the step S160, it is determined whether the iteration isended, and according to the results, the process moves into the step S20(B) or finished. If there is no any value to be fetched from the firststage buffer section 21, the iteration number is checked. If theiteration number is not the set iteration number, the input signal issubsequently processed.

FIG. 4 is a block diagram of a matched filter code searcher using theregion search shown in FIG. 2, and has the structure which the searcher43 having the region searching function according to the presentinvention is added to the general structure having a matched filter 40,an energy value converting section 41, and an index generating section42.

The matched filter 40 and the energy value converting section 41 whichis the general component store the input signals, correlate the inputsignals with a given pattern, and adds these correlated values, and theobtained inphase and quadrature values are squared and added them toconverted to the energy value, in order to remove the phase component.In addition, the location value obtained in the index generating section42 is stored in the searcher 43 shown by the present invention, and thefinally obtained location value having a large energy value isoutputted. In this case, the index generating section 42 separatelygenerates the location values and the generated location values are usedas the location value of the searcher 43.

As an example using the structure shown in FIG. 4, there is anasynchronous IMT-2000 cell searcher. A primary synchronization channelwhich the cell searcher searches has 2560 chip periods, the channel istransmitted during the 1/10 period, and the channel is not transmittedduring the remaining period. In such non-continuous transmission channelstructure, because every values of the transmission signals must be usedby using the matched filter and the input hypothesis location value mustbe obtained in order to receive the transmission signal, thesignal-to-noise ratio of the signal becomes deteriorated. Accordingly,at the same hypothesis location energy values iteratively obtained atthe searched region must be added. Also, because the correlated valuesfor the hypothesis location are generally obtained at the ½ chipinterval by the correlation characteristics of the spread code in thegiven searched region, 5120 energy values must be stored in all.

In addition, as another example, when the size of the matched filterrestricts the implementation of the hardware or the size of the matchedfilter can not become larger than the certain value by the non-coherentcharacteristics, the region must be iteratively searched to obtain thehypothesis value. Accordingly, by using the above-mentioned structureaccording to the present invention, the effective implementation thereofcan be accomplished.

FIG. 5 is a block diagram of a correlator code searcher using the regionsearcher shown in FIG. 2, and has the structure which the searcher 54having the region searching function according to the present inventionis added to the general structure having a correlator 50, a energyconverting section 51, a code generating section 52, and an indexgenerating section 53.

The correlator code searcher shown in FIG. 5 obtains the energy valuedepending on the hypothesis location value by using the correlator 50.Like this, in case of using the correlator 50, the code generatingsection 52 which is the local spread signal generator must be used, andthe code generating section generates spread code in accordance with thehypothesis location value.

This method reduce the implementation complexity thereof in comparisonwith the method using the matched filter shown in FIG. 4, but theprocessing speed thereof is remarkably increased because the signals inthe integration region of the correlator 50 are collected in order toobtain the value corresponding to the one hypothesis location value. Inorder to remove the phase component included in the obtained correlatedvalue, the energy converting section 51 squares the correlated valuesand adds them to generate the energy value.

Also, the energy values for every hypothesis location value are stored,and, when the given region is iteratively searched and the energy valuesare interatively generated by the hypothesis location values, theseenergy values are processed by the correlator to find the desired largelocation value by using the searcher 54.

As mentioned above, the present invention can remarkably reduce theimplementation complexity thereof by storing the energy valuecorresponding to the same hypothesis location value by using a searcherhaving divided two buffers, without simply using a memory, when apredetermined region is iteratively searched.

In addition, the present invention can remarkably reduce theimplementation complexity thereof in case where the region isiteratively searched in the state of the deteriorated signal-to-noiseratio to find the energy value at one hypothesis location and in casewhere the region must be iteratively searched because of the restrictionwhich the size of the matched filter can be not increased.

1. A region searcher comprising: an input signal converting section forreceiving an energy value and converting the energy value; a firstbuffer section for storing a first converted energy value converted bysaid input signal converting section; a second buffer section forstoring an added value obtained from a second converted energy valueconverted by said input signal converting section; a comparing sectionfor comparing an input location value with a location value stored insaid second buffer section in order to search the location value storedin the second buffer section; an output signal converting section forconverting an energy value stored in said second buffer section; and anadder for adding the second converted energy value output from saidinput signal converting section and the converted energy value outputfrom said output signal converting section and storing the added valueto the second buffer section.
 2. The region searcher according to claim1, wherein said first buffer section stores large energy values by anallowable number among searched energy values, in a firstly searchedregion, and stores large location values by the allowable number amonginput location values except for location values stored in said secondbuffer section, in an iteratively searched region.
 3. The regionsearcher according to claim 2, wherein said searched region is theregion of a predetermined hypothesis location.
 4. The region searcheraccording to claim 1, wherein said second buffer section stores alargest energy value among the energy values, in firstly searchedregion, and stores the input energy value thereat if the input locationvalue is equal to the location value stored in said second buffersection, in iteratively searched region.
 5. The region searcheraccording to claim 3, wherein said searched region is the region of apredetermined hypothesis location.
 6. The region searcher according toclaim 1, wherein said input signal converting section converts the inputenergy value in accordance with a predetermined energy value ratio ifthe input location value is not equal to the location value stored insaid second buffer section.
 7. The region searcher according to claim 1,wherein said adder adds the second converted energy value output fromsaid input signal converting section and the energy value output fromsaid output signal converting section and stores the added energy valueto said second buffer section, if the input location value is equal tothe location value stored in said second buffer section.
 8. The regionsearcher according to claim 1, wherein the first converted energy valueis compared with the energy value stored in said first buffer section ifthe input location value is not equal to the location value of saidsecond buffer section, and, the first converted energy value is replacedwith a smallest energy value of said first buffer section if the firstconverted energy value is larger than the energy value stored in saidfirst buffer section.
 9. A method of driving a region searchercomprising the steps of: (a) setting variables; (b) receiving an inputenergy value and an input location value by using an input signalconverting section and an index comparing section; (c) comparing saidinput location value with a location value stored in a second buffersection by using said index comparing section; (d) converting said inputenergy value by a first predetermined energy value ratio by using saidinput signal converting section; if said input location value is notequal to the location value stored in said second buffer section in the(c) step; (e) comparing the energy value converted in the (d) step witha smallest energy value stored in a first buffer section, and, if theconverted energy value is larger than the smallest energy value storedin said first buffer section, replacing said converted energy value withthe smallest energy value among energy values stored in said firstbuffer section, and, if the converted energy value is not larger thanthe smallest energy value stored in said first buffer section, receivinga new energy value; (f) converting the input energy value and the energyvalue stored in said second buffer section by using a secondpredetermined energy value ratio if said input location value is equalto the location value stored in said second buffer section in the (c)step; and (g) removing the energy value stored in a location of saidsecond buffer section corresponding to the input location value in orderto store an added energy value computed by adding the energy valuesconverted in the (f) step, aligning the energy values in the secondbuffer section in accordance with the size thereof, and storing saidadded energy value thereto.
 10. The method of driving a region searcheraccording to claim 9, wherein further comprising: (c′) reading theenergy values stored in said first buffer section in stored order andinserting 0 to the location thereof, if the input location value is notincluded in the searched region in the (c) step; (d′) comparing theenergy value read from said first buffer section in the (c′) step withthe energy value stored in said second buffer section; (e′) removing asmallest energy value among the energy values stored in said secondbuffer section if the energy value read from said first buffer sectionis larger than the energy value stored in said second buffer section inthe (d′) step, downwardly shifting the energy values smaller than theenergy value read from said first buffer section one by one, among theenergy values stored in said second buffer section, and inserting theenergy value of said first buffer section to an empty space of the saidsecond buffer section; (f′) determining whether there is an energy valueto be read from the second buffer section, if the energy value read fromsaid first buffer section is smaller than the energy value stored insaid second buffer section in the (d′) step and reading the energy valuefrom said second buffer section if there is an energy value to be readfrom the second buffer section; and (g′) searching the energy valuesstored in said first buffer section if there is no any energy value tobe read from said second buffer section in the (f′) step and determiningwhether every energy values stored in said first buffer section areread.
 11. The method of driving a region searcher according to claim 9,wherein the (g) step of removing the energy value comprises the step ofcomparing said added energy value with the energy values stored in saidsecond buffer section in descending order, and, if the energy valuesstored in the second buffer section smaller than the added energy valueis detected, downwardly shifting said energy values smaller than theconverted energy value one by one to store the added energy valuethereto.
 12. A code searcher comprising: a matched filter for receivinginput signals including in-phase and quadrature phase components andoutputting the correlated value of said input signals; an energyconverting section for squaring the in-phase and the quadrature phaseand adding them to be converted to an energy value, in order to removethe in-phase and quadrature phase components included in said correlatedvalue; an index generating section for generating a location valuecorresponding to said energy value; and a region searcher for receivingthe energy value output from said energy value converting section andthe location value generated by said index generating section to detecta code spread signal, the region searcher comprising: an input signalconverting section for receiving an energy value and converting theenergy value; a first buffer section for storing a first convertedenergy value converted by said input signal converting section; a secondbuffer section for storing an added value obtained from a secondconverted energy value converted by said input signal convertingsection; a comparing section for comparing an input location value witha location value stored in said second buffer section in order to searchthe location value stored in the second buffer section; an output signalconverting section for converting an energy value stored in said secondbuffer section; and an adder for adding the second converted energyvalue output from said input signal converting section and the energyvalue output from said output signal converting section and storing theadded value to the second buffer section.
 13. A code searchercomprising: a correlator for receiving input signals including in-phaseand quadrature phase components and outputting the correlated value ofsaid input signals; a code generating section for generating andoutputting a code spread signal in successive code searching regionswithout the loss of calculation time; an energy converting section forsquaring said in-phase and quadrature phase and adding them to beconverted to an energy value in order to remove the in-phase andquadrature phase components included in said correlated value; an indexgenerating section for generating a location value corresponding to saidenergy value; and a region searcher for receiving the energy valueoutput from said energy value converting section and the location valueof said index generating section to detect the code spread signal, theregion searcher comprising: an input signal converting section forreceiving the energy value and converting the energy value; a firstbuffer section for storing a first converted energy value converted bysaid input signal converting section; a second buffer section forstoring an added value obtained from a second converted energy valueconverted by said input signal converting section; a comparing sectionfor comparing an input location value with a location value stored insaid second buffer section in order to search the location value storedin the second buffer section; an output signal converting section forconverting an energy value stored in said second buffer section; and anadder for adding the second converted energy value output from saidinput signal converting section and the energy value output from saidoutput signal converting section and storing the added value to thesecond buffer section.